1. Field of the Invention
The present invention relates to a tube joint capable of introducing and discharging, for example, a pressure fluid via a passage in communication therewith, by coupling and connecting the tube joint, for example, to a fluid pressure-operated apparatus such as a cylinder.
2. Description of the Related Art
The fluid pressure-operated apparatus such as a cylinder has been hitherto in widespread use in order to drive and control an object by utilizing, for example, compressed air. In general, the fluid pressure-operated apparatus is usually provided with a pressure fluid inlet/outlet port for introducing and discharging the pressure fluid. Therefore, a tube joint, which is used to connect each tube passage, is connected to the pressure fluid inlet/outlet port. For example, when a tube, which communicates with a pressure fluid supply source, is connected to the tube joint, the pressure fluid can be supplied from the pressure fluid supply source to the fluid pressure-operated apparatus.
Such a tube joint concerning the conventional technique is shown in FIG. 5 (see, for example, Japanese Patent Publication No. 51-14166).
The tube joint is provided with a socket 2 which has first, second, third, and fourth holes 1a to 1d formed to have a concentric configuration, and a collar 4 which is held in the first hole 1a of the socket 2 and which is formed with an inclined surface 3. A tightening member 6, which has four flexible jaws 5, is internally fitted to the collar 4. Each of the jaws 5 is formed with a knife edge 8 to bite into the outer circumferential surface of a tube 7 in cooperation with the inclined surface 3 of the collar 4 so that the tube 7 is prevented from disengagement. The tightening member 6 is provided displaceably along the axial direction of the collar 4.
A packing ring 9, which is formed of, for example, a rubber material, is installed to the second hole 1b which is disposed adjacent to the jaws 5. The packing ring 9 surrounds the outer circumferential surface of the tube 7 so that it functions as a seal.
When the tube 7 is coupled to the socket 2, it is enough that the tube 7 is simply inserted into the tightening member 6. Accordingly, the jaws 5 are expanded radially outwardly by the thrust force which is exerted when the tube 7 is forcibly inserted. Further, the tube 7 passes through the packing ring 9, and it arrives at the third hole 1c. Subsequently, when the tube 7 is pulled in a direction opposite to the insertion direction, or when the pressure is applied to the tube 7, then the knife edge 8 of the tightening member 6 bites into the surface of the tube 7. Thus, the tube 7 is fastened.
When the tube 7 is disengaged from the socket 2, the force in the direction of the arrow F is applied to the lower end of the tightening member 6 to apply the thrust force to the tube 7. Thus, the tube 7 can be pulled out in the direction opposite to the insertion direction.
However, the tube joint concerning the conventional technique described above involves the following inconvenience. That is, when the tube 7 is inserted, then the jaw 5 of the tightening member 6 abuts against the packing ring 9, and the packing ring 9 is pressed thereby. As a result, the packing ring 9 is expanded radially inwardly, and it is difficult to insert the tube 7.
The inconvenience described above is caused probably because of the following reason. That is, when the tube 7 is inserted, the tightening member 6 is displaced along the axial direction of the collar 4 to press the packing ring 9. As a result, the packing ring 9 is expanded radially inwardly. Therefore, the tube 7 to be inserted is tightened inwardly by the expanded packing ring 9.
Further, the tube joint concerning the conventional technique involves the following inconvenience. That is, the packing ring 9 is not fixed, and it is provided slidably along the second hole 1b. For this reason, any dust is generated due to the sliding movement of the packing ring 9. As a result, it is difficult to use the tube joint concerning the conventional technique in an environment in which cleanness is required, for example, in a clean room.
A general object of the present invention is to provide a tube joint which avoids any expansion of a seal member upon insertion to make it possible to easily insert a tube.
A principal object of the present invention is to provide a tube joint which avoids any dust formation otherwise caused by a seal member to make it possible to preferably use the tube joint in an environment in which cleanness is required.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.